Semifinished product with a metallic foam core

ABSTRACT

Rollers and cylinders that are useable in rotary printing presses are made using hollow tubular casings having metallic foam cores. The casings and cores are made separately. The cores are then placed inside the casing and the two are secured together in a force-transmitting manner.

[0001] The invention relates to semifinished products with a metallic foam core, and to a process for producing same.

[0002] Processes for producing a metallic foam have become known from U.S. Pat. No. 3,087,807 A and DE 40 18 360 C1. U.S. Pat. No. 3,087,807 A shows that a hollow body can be filled with metallic foam by generating the metallic foam inside the hollow body.

[0003] DE 44 43 840 C2 shows an impact protector for a motor vehicle paneling element. In this case a cushion made of a light metal foam is completely enclosed in a casing. The document does not show whether and how the light metal foam is fastened in the interior of the casing.

[0004] A way of producing plates in sandwich construction can be taken from DE-OS 21 19 490. Metallic foam plates arranged between cover plates are used. The cover plates are fastened on the metallic foam plate.

[0005] Rotating cylinders, for example in the form of paper guide rollers, or hollow cylinders, for example as printing or rubber blanket cylinders, are known in connection with rotary printing presses, for example. Paper guide rollers, for example, are driven by means of the web itself, which is to be guided by them. This can result in an unintentional effect on the print carrier web, i.e. for example a paper web or foil web since, as stated, the energy for accelerating or braking must be applied to the cylinders themselves via the print carrier web. Added to this are the difficulties that, on the one hand the paper web widths continue to become wider (for example 3.80 m) and, on the other hand, the speeds of the print carrier webs are also continuously increased and in the meantime have reached 18 m/sec.

[0006] It is the object of the invention to provide semifinished products with metallic foam cores for rollers and cylinders intended for rotating operation, and a process for producing the same.

[0007] In accordance with the invention, this object is attained by the characteristics of claims 1 and 8.

[0008] The advantages to be gained by means of the invention in particular reside in that rollers, cylinders, or the like, which are suitable for rotary operations at high numbers of revolutions and having a metallic foam core can be created, which can have a casing which is not stressed by the high temperatures (for example 500° C.) required for creating a metallic foam. It is possible to fill pairs of metals, for example rollers made of steel with an aluminum foam, without a relative movement between the interior surface of the roller and the metallic foam surface occurring in the course of rotary operations of the rollers/cylinders during acceleration and braking. It is therefore possible to use all advantages provided by filling the rollers/cylinders with a metallic foam, without it being necessary to overstress them thermally.

[0009] Thus it is possible, for example, to omit an individual electric motor drive, for example, for the paper guide rollers.

[0010] Exemplary embodiments of the semifinished product of the invention and the process for producing the same will be described in what follows:

[0011] It is common to all processes in accordance with the invention that a metallic foam core is inserted into a tube-shaped body, open on one or both ends, of any arbitrary cross section, for example a roller or a cylinder.

[0012] The tube-shaped body—called casing in what follows—can be made of any arbitrary material, for example metal (steel, aluminum, brass, etc.), plastic material, for example polyamide, ceramic material or paper. The cross section of its interior can have any arbitrary geometric shape: circular, square, with single or multiple longitudinal grooves, as a counterpart of a splined shaft (single spline, multiple spline), serrated shaft, K-profile shaft, etc.

[0013] Thus, the cross section of the interior of the casing can be arbitrary. However, it must be designed in such a way that it is possible to introduce one or several metallic foam core(s) through one of the openings at the ends of the rollers/cylinders or, with multi-part metallic foam cores, from both end openings.

[0014] The metallic foam core is produced at a location separate from the casing and is later introduced into the interior of the casing.

[0015] The metallic foam core can be produced in several ways, known per se, for example in accordance with the processes described in DE 40 18 360 C1. However, with the processes of the invention, foaming takes place outside of the casing to be filled.

[0016] In accordance with the invention, the metallic foam core is introduced in a quasi finished state into the interior of the casing and fastened either on the entire interior surface of the latter, or only on portions of the interior surface of the casing. The connection between the outer surface of the metallic foam core and the interior surface of the casing must be designed such that it allows, at least partially, a force transfer between the inside of the casing and the metallic foam core via its exterior surface.

[0017] The connection can be designed as a releasable connection or a non-releasable connection.

[0018] The releasable connections can be interlocking connections, for example profiled connections, spring connections, but screw connections, are also suitable. In the just mentioned cases it is necessary to match the inner surfaces of the casing and the outer surface of the metallic foam core to each other, for example interior threads in the casing, exterior threads on the metallic foam core, providing the surface of the metallic foam core with a taper key, or as a “multi-splined shaft”, and the interior surface of the casing with corresponding groove(s). Frictional connections in the form of a cone connection (outer cone on the metallic foam core, inner cone on the casing) would also be possible.

[0019] The releasable connections can also be designed to be force-locking in that a shrinkage fit is used in addition. To this end, when using metallic casings the casing is heated and the metallic foam core is inserted into the interior of the casing. The metallic foam core can additionally be cooled. A very solid, interlocking force-locking connection is created between them after temperature equalization.

[0020] However, the connection between the casing and the metallic foam core can also be provided as a connection directly between the materials involved, for example an adhesive connection, but also as a force-locking connection, for example shrinkage fit, or as a combined material/force-locking connection. In the latter case, a casing, which for example has been heated, is pushed onto a metallic foam core coated with an adhesive—for example a metallic adhesive on the chemical basis of a dimethylacrylate ester (for example LOCTITE 574 (a tradename of the LOCTITE company)—. In this case the casing is made of steel, for example, the metallic foam an aluminum foam, for example. A very solid shrinkage/adhesive connection occurs after cooling and curing of the adhesive. Anaerobic adhesives are particularly suited here, which make possible the connection between different metals in a simple manner.

[0021] It must be assured in connection with all described types of connections that there is no possible play between the casing and the metallic foam core, or that such could occur. 

1. A process for producing semifinished products for rollers, cylinders intended for rotary operation and having a hollow casing, characterized in that a metallic foam core produced outside of the casing is inserted into the interior of the casing and is fastened in a force-transmitting manner on the interior surface of the latter.
 2. The process in accordance with claim 1, characterized in that the metallic foam core is fastened via its surface to the inside of the case by means of a force-locking connection.
 3. The process in accordance with claim 1, characterized in that the metallic foam core is fastened via its surface to the inside of the case by means of an interlocking connection.
 4. The process in accordance with claim 1, characterized in that the metallic foam core is fastened via its surface to the inside of the case by means of a connection directly between the materials involved.
 5. The process in accordance with claim 1, characterized in that the metallic foam core is fastened via its surface to the inside of the case by means of a combination of an interlocking connection and a connection directly between the materials.
 6. The process in accordance with claim 4, characterized in that the metallic foam core and the hollow casing are connected by means of an adhesive connection.
 7. The process in accordance with claim 2, characterized in that the metallic foam core is introduced into the hollow casing by employing a temperature difference between the metallic foam core and the hollow casing.
 8. A semifinished product for roller or cylinders with a hollow casing, characterized in that a metallic foam core, which was produced outside of the casing, is fastened in a force-transmitting manner on the inner surface of the hollow casing.
 9. The semifinished product in accordance with claim 8, characterized in that an inner surface of the hollow casing is connected at least partially with a surface of the metallic foam core.
 10. The semifinished product in accordance with claim 9, characterized in that the inner surface of the hollow casing is connected in its entirety with the surface of the metallic foam core.
 11. The semifinished product in accordance with claims 8 to 10, characterized in that the metallic foam core completely fills the entire cross section of the hollow casing.
 12. The semifinished product in accordance with claims 8 to 11, characterized in that the semifinished product is used for producing rotating rollers and cylinders.
 13. The semifinished product in accordance with claims 8 to 12, characterized in that the semifinished product is used for producing a roller or a cylinder.
 14. The semifinished product in accordance with claims 8 to 12, characterized in that the roller or the cylinder are used in a printing press. 